Field of the Invention
Embodiments of the present invention relate to a semiconductor memory device and a memory system, and more particularly to a semiconductor memory device and a memory system which can be operated in various operational units.
Description of the Related Art
A semiconductor memory device may be implemented using a semiconductor material such as silicon (Si), germanium (Ge), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), etc. Semiconductor memory devices are generally classified into a volatile memory device and a non-volatile memory device.
Data stored in a volatile memory is lost when power supply is stopped. Volatile memories may be classified into a static RAM (SRAM), a dynamic RAM (DRAM), a synchronous DRAM (SDRAM), etc. On the other hand, data stored in a non-volatile memory is not lost even when power supply is stopped. There are a variety of non-volatile memory devices such as a read only memory (ROM), a programmable read-only memory (PROM) device, an erasable programmable read-only memory (EPROM) device, an electrically erasable programmable read-only memory (EEPROM) device, a flash memory device, a phase change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), etc. The integration degree of a semiconductor memory device is considered very important in affecting throughput or performance of the device.